liner for a turbine section, a turbine section, a gas turbine engine and an aeroplane provided therewith

ABSTRACT

A liner for a turbine section includes a first wall, a plurality of webs interconnected with and projecting from the first wall, and a plurality of cooling channels, each of the cooling channels being delimited by two adjacent webs and the first wall, wherein each cooling channel presents a height corresponding to the height of its delimiting webs, and a width corresponding to the distance between its delimiting webs. At least one of the cooling channels has a width/height ratio of below 5 or/and the material of the webs has a higher thermal conductivity than the material of the first wall. A turbine section, a gas turbine engine and an aeroplane provided with such a liner are also disclosed.

BACKGROUND AND SUMMARY

The present invention relates to a liner for a turbine section, saidliner comprising a first wall, a plurality of webs interconnected withand projecting from said first wall, and a plurality of coolingchannels, each of said cooling channels being delimited by two adjacentwebs and said first wall, wherein each cooling channel presents a heightcorresponding to the height of its delimiting webs, and a widthcorresponding to the distance between its delimiting webs.

The invention also relates to a turbine section provided with the linerof the invention, a gas turbine engine provided with a turbine sectionaccording to the invention, and an aeroplane provided with a gas turbineengine according to the invention.

Preferably, the turbine section is a load-carrying frame arrangedadjacent to at least one gas turbine, possibly but not necessarilylocated between two adjacent turbines, i.e. a high pressure turbine anda low pressure turbine. The load-carrying frame may be a so-calledturbine centre frame, which may comprise an inner wall, an outer walland a plurality of radial struts extending between said inner and outerwalls. Said frame forms an annular channel, subdivided by said struts,through which the gases from an upstream combustion chamber passes, saidgases thereby also passing the turbine or turbines of the engine. Theliner according to the invention may comprise sheets or plates that areto be applied as a heat-protecting cover on the surface of any of saidinner wall, outer wall and struts, said surface being a surface directedtowards said annular channel.

Typically, the diameter of the gas turbine section of the invention willbe in the range of one to two metres. However the invention may beapplicable to corresponding gas turbine sections with dimensions outsidesaid range.

A so called turbine centre frame of a turbine section of a gas turbineengine is often comprised by a load-Carrying part which is provided withsheets or plates that ensures the cooling thereof. These plates orsheets are not load-carrying, i.e. the load-carrying function and thecooling function are, mainly, divided on different parts of saidsection.

Normally, said plates or sheets comprise a first wall and a second walldivided and interconnected by longitudinal webs, said webs delimitingparallel channels between the first and second walls. The first wall isdirected towards the channel through which hot gases are flowing throughthe turbine, while the second wall is directed towards the part to whichthe plate or sheet is attached.

A problem encountered by these plates is that their cooling ability isdelimited due to inherent limitations of the structure thereof.Normally, cooling air is to be conducted through the channels of saidplates, but there are limitations as to the amount of air that can beblown through the channels, and the pressure fall of the air in thechannels also sets a limit to the cooling rate that may be achieved.Therefore, the plates become very hot, and, accordingly, they areconventionally made of a high temperature resistant material.

In order to lower the temperature of the plates, the heat flow throughand out of the plates should be increased. Principally, there are onlytwo possible ways accessible in order to achieve such a goal, namelyeither to improve the cooling, as for example achieved by means of theflow of cooling air, or to increase the heat conductibility of theplates.

Conventional solutions are based on the principle that cooling air drawnor blown through the channels of the plate are to absorb heat throughconvection from the wall adjacent to the hot combustion gases. However,since normally the delimitations of the engine do not permit a largeflow of air of high velocity through the channels of the plates, it willnot be easy to achieve the set target of lowering the wall temperatureby increasing the cooling through the cooling medium in the channels.

It is desirable to present a liner as initially defined, the design ofwhich is such that it presents an improved ability of conducting heatthere through, such that, for a given temperature of the gases to whicha first wall thereof is subjected during operation, the temperature ofsaid first wall is decreased in relation to corresponding liners ofprior art.

According to an aspect of the present invention, a liner is provided,characterised in that at least one of said cooling channels has awidth/height ratio of below 5. The width/height ratio is markedly lowerthan what is common in prior art, as far as the applicant knows. Bylowering said width/height ratio in relation to prior art, a largerproportion of the heat than before will be conducted to and through thewebs, and a larger proportion of the heat than before will betransferred by means of convection from the webs to the cooling mediumflowing through said channels during engine operation. Preferably, theliner comprises a plurality of parallel cooling channels, each delimitedby two neighbouring webs, wherein a substantial part of said channels,preferably a majority thereof, and most preferably all of said channelspresent the width/height ratio. It is also preferred that both of theneighbouring webs that delimit said at least one cooling channel havesubstantially the same height. It is further preferred that at least themajority, and most preferably all of the webs present the same height,as measured in a direction perpendicularly from the surface of the firstwall from which they project.

Preferably, the width/height ratio is below 3, even more preferablybelow 1, or, most preferably said ratio is below 0.5. It is alsopreferred that the width/height ratio is above 0.1.

Preferably, for said at least one channel, the ratio between the widthof said at least one channel and the width of at least one of itsdelimiting webs is <2. Preferably, the width of said at least onechannel and the width of each of its delimiting webs is <2. Among aplurality of parallel channels, these features are preferred for asubstantial part thereof, preferably a major part thereof, and mostpreferably all of said channels.

According to a preferred embodiment, the width, or thickness, of each ofsaid webs that delimit said at least one channel is below 2 mm.Preferably, among a plurality of such webs, a substantial part thereof,preferably a major part thereof, and most preferably all thereof presentsaid width.

It is further preferred that the height of said at least one channel isabove 2 mm., and preferably below 15 mm.

Preferably, the liner comprises a second wall interconnected with saidfirst wall through at least some of said webs and located opposite tosaid first wall. Thereby, the liner present a number of separate coolingchannels, each delimited by the first wall, the second wall and twoneighbouring webs. Preferably, a substantial part of the webs, morepreferably a major a part, and most preferably all of said websinterconnect said first and second walls, thereby being able to conductheat from the first wall to the second wall, and also mechanicallystabilising the liner.

The object of the invention is also achieved by means of the initiallydefined liner, characterised in that the material of the webs has ahigher thermal conductivity than the material of the first wall.Thereby, a relatively larger proportion of heat than otherwise will betransferred through the webs, and, accordingly, a larger proportion ofthe heat will be transferred through convection from the webs to thecooling medium flowing through the channels of the liner. Preferably,such a design is combined with a liner design with the one or more ofthe features discussed herein.

According to a preferred embodiment, the material of the first wall hasa higher temperature resistance than the material of the webs. Thereby,the ability of the liner to resist the immediate affection of hot gasesflowing through turbine section in which the liner is positioned duringoperation may be provided for. The material of the webs can then beoptimised with regard to other properties relevant for the functionthereof, such as thermal conductivity.

Preferably, the material of the first wall comprises steel. Thereby, atleast a layer of the first wall that is to be directly subjected and incontact with the hot gases flowing through the turbine section may,preferably, be made of steel, since the latter will provide acceptablemechanical as well as heat resistant properties.

Preferably, the material of the webs comprises copper or a copper alloyas a main constituent. Thereby an improved thermal conductivity of thewebs is provided for.

According to an alternative embodiment, the material of the webscomprises a material the density of which is lower than that of thefirst wall. Since weight saving is an important issue in connection tothe design of gas turbine engines to be used in vehicles, in particularaircrafts, a lighter material than that of the first wall might bepreferred for the webs, especially since the number of webs and thetotal volume occupied thereby is likely to increase with a design inaccordance with the invention.

According to a preferred embodiment the material of the webs comprisesaluminium as a main constituent, due to an advantageous combination oflight weight, high thermal conductivity, machinability, and availabilityof the latter. Depending on the cooling air conditions, aluminium alloysmay be used in order to secure high temperature material propertieswhile maintaining a higher conductivity and lower density than steelmaterials.

A mixture of copper and aluminium may be used, i.e. copper in the websand aluminium in the outer wall or a part of the outer wall, i.e. thewall which is not facing the hot gases. In order to facilitate the useof aluminium, a thermal barrier coating (TBC coating) may be applied tothe hot gas side.

The invention also includes a turbine section, characterised in that itcomprises a liner according to the invention. Preferably, the liner isattached to a load-carrying part of said turbine section, whereby saidpart may be any of a radial strut connecting an inner wall and an outerwall of said turbine section, an inner wall of the turbine section, oran outer wall of the turbine section. Preferably, the first wall of theliner is turned towards the turbine chamber, such that it will besubjected to hot gases flowing therein during turbine operation.

Preferably, the turbine section comprises a load-carrying frame arrangedadjacent to at least one gas turbine, normally a frame located between alow pressure turbine and a high pressure turbine as seen in the gas flowdirection through the engine.

Further features and advantages of the present invention will bepresented in the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a first embodiment of a gasturbine engine provided with a liner according to the invention,

FIG. 2 is a perspective view showing a turbine section to be providedwith a liner according to the invention,

FIG. 3 shows a part of the turbine section of FIG. 2, provided with aliner according to the invention,

FIG. 4 is a partly cut part of a turbine section provided with a lineraccording to the invention,

FIG. 5 is a cross-sectional view of a liner of the invention, accordingto a first embodiment as arranged adjacent to a load carrying part of aturbine section,

FIG. 6 is a cross-sectional view of a liner of the invention, accordingto a second embodiment, as arranged adjacent to a load carrying part ofa turbine section, and

FIG. 7 is a cross-sectional view of a liner according to prior art, asarranged adjacent to a load carrying part of a turbine section.

DETAILED DESCRIPTION

FIG. 1 is an oversight view of a gas turbine engine 1 according to theinvention provided with a turbine section 2 provided with a lineraccording to the invention. The gas turbine engine 1 shown in FIG. 1 isof conventional construction and comprises, in axial flow series, an airintake 3, low pressure compressor 4, high pressure compressor 5,combustion equipment 6, high pressure turbine 7, low pressure turbine 8and an exhaust outlet 9. During operation, the high pressure compressoris driven by the high pressure turbine via a first hollow shaft 10.Similarly, the low pressure compressor 5 is driven by the low pressureturbine via a second hollow shaft 11 which is coaxially disposed withinthe first hollow shaft 10.

The gas turbine engine 1 operates in the conventional manner whereby airdrawn in through the air intake 3 is compressed by the low pressurecompressor 4 before passing into the high pressure compressor 5 where itis compressed further. The compressed air then flows into the combustionequipment 6 where it is mixed with fuel and the mixture combusted. Theresultant hot combustion products then expand through the high and lowpressure turbines 7, 8 before being exhausted to the atmosphere throughthe exhaust nozzle 9.

The turbine section 2 to be provided with a liner according to theinvention is a load-carrying frame 12 (see FIG. 2) arranged in a part ofthe turbine housing in which the gases flowing from the combustionchamber still have such a high temperature that the material of theload-carrying frame 12 has to be protected from the heat by means of aprotective liner. The turbine section 2 is arranged downstream thecombustion chamber as seen in the gas flow direction the gas turbineengine. The load-carrying frame 12 forms part of the stator of theengine. As in this embodiment, the load-carrying frame 12 provided withthe liner according to the invention is located downstream and adjacentthe high pressure turbine 7.

FIG. 2 shows the load-carrying frame 12 more in detail. It comprises aninner wall 13, an outer wall 14 and struts 15 extending between theinner wall 13 and the outer wall 14. The inner wall 13 and the outerwall 14 delimits an annular channel which is subdivided by the struts 15into segments and through which the still hot gases from the combustionchamber pass during engine operation. Thereby, said walls 13, 14 andstruts 15 are subjected to a significant heat.

In order to decrease the heat to which the load-carrying parts 13, 14,15 of the frame 12 are subjected, a liner 16 according to the inventionis attached to said parts 13, 14, 15 (see FIGS. 3 and 4). The liner 16comprises plates or the like, a periphery of which matches the peripheryof the load carrying part onto which they are to be attached. Aplurality of plates may be attached to said parts and interconnected inorder to form the liner 16. Preferably, there is provided a gap betweenthe liner 16 and the load carrying part 13, 14, 15 which it covers.However, the arrangement of the liner 16 onto said parts 13, 14, 15 maybe of a kind known per se, and will therefore not be discussed more indetail in this context.

FIG. 4 shows one of the struts 15, and indicates how the strut 15 isprovided with said liner 16. The liner 16 covers the exterior of thestrut 15, thereby protecting it from the heat of hot gases flowingthrough the engine during engine operation.

FIGS. 5 and 6 show the design of the liner 16 more in detail. The liner16 comprises a first wall 17, a second wall 18 and a plurality of webs19 connecting and separating the first and second walls 17, 18. Channels20 extending in parallel are delimited by said walls 17, 18 and webs 19.FIGS. 5 and 6 show the liner 16 as attached to the inner wall 13 of theframe 12. However, it should be understood that a correspondingprovision of the liner 16 on the outer wall 14 and the struts 15 is alsoincluded in the invention.

The first wall 17 of the liner 16 is directed towards, and subjected todirect contact with the hot gases flowing through the turbine section 2during engine operation. The second wall 18, on the other hand, isturned towards the load-carrying part 13, 14, 15 to which the liner 16is attached or which is covered by the liner 16. Preferably, thelongitudinal direction of the channels 20 of the liner 16 attached tothe inner wall 13 and the outer wall 14 of the frame 12 generallycoincides with the longitudinal direction of said walls 13, 14, i.e. thelongitudinal direction of the engine 1 and the gas flow directionthrough the latter. The longitudinal direction of the channels 20 of theliner 16 attached to the struts 15 may, however coincide with thelongitudinal direction of said struts 15, i.e. from the inner wall 13 tothe outer wall 14, i.e. crosswise to the gas flow direction through theengine 1.

Moreover, there should be provided means (not shown) for introducing aflow of a cooling medium into said channels 20, and means for lettingsaid cooling medium out of the channels 20. Such means may include anykind of compressor, a manifold via which the cooling medium isintroduced into the channels 20 of the liner 16, and a conduit throughwhich the cooling medium is guided from the compressor to said manifold.Preferably, the inlets to the channels 20 are closed towards the hotgases flowing through the turbine section 2 that comprises said frame12. However, the outlets of the channels 20 might communicate with theturbine chamber in which the hot gases are to flow during engineoperation, thereby possibly providing for a film cooling effect on theturbine wall downstream the section 2 provided with said liner 16.Alternatively, there might be provided subsequent liner segments in thelongitudinal direction of the engine 1, whereby cooling air from theoutlet of an upstream segment is permitted to enter the turbine chamberand provide for film cooling of a subsequent downstream liner segment.

The cooling channels 20 has a width/height ratio of below 1, preferablybelow 0.75, and most preferably below 0.5. In this context, the width isreferred to as the dimension thereof in a direction generally parallelwith the plane of the first and second walls 17, 18, while the height isreferred to as the dimension thereof in a direction perpendicular tosaid plane or planes. However, it should be understood that the firstand second walls 17, 18 are not likely to be absolutely flat or plane,but will, in most cases, present a certain curvature, following thecurvature of the load-carrying part 13, 14, 15 to which the liner 16 isattached or which is covered thereby. In other words, the plane inrelation to which the height direction may be the normal may present acurvature.

In the embodiment shown in FIG. 5, the material of the first wall 17,the second wall 18 and the webs is the same, preferably high temperaturesteel material such as haynes188 or Haynes 230.

In the embodiment shown in FIG. 6, on the other hand, the material ofthe first wall 117 or at least of a part thereof that is directlysubjected to flow of hot gases through the turbine section 2, differsfrom the material of the webs 19 connected thereto. Preferably, thematerial of the first wall 117 has a higher temperature resistance thanthe material of the webs 19, while, on the other hand, the material ofthe webs 19 has a higher thermal conductivity than the material of thefirst wall 117. By using a material of higher thermal conductivity inthe webs 19, the webs 19 may contribute to the overall conduction ofheat to a higher degree than before. The suggested design will permit animproved conduction of heat through the webs 19, from which a part ofthe heat may be transferred to the cooling medium by means of convectionand a part of the heat may be transferred the second wall 18. Since alarger amount of the heat may now be transferred to the cooling mediumvia the high-conductive webs 19, a lower amount of heat than earlierwill now be transferred to the second wall 18 through said webs 19.Since less heat than otherwise is transferred from the second wall 18 tothe load-carrying part 13, 14, 15 of the frame 12 to which the liner 116is attached, said load-carrying part 13, 14, 15 of the frame 12 will beless subjected to heat and, accordingly, better able to fulfil itsload-carrying task, thanks to a lower temperature.

Preferably, the material of the first wall 117 or said part thereofcomprises steel as its main constituent, while the material of the webs19 comprises copper as its main constituent. However, other combinationsof materials of the first wall 117 and the webs 19 might as well beconceived and be within the scope of the invention. Preferably, thematerial of the second wall 18 is the same as that of the webs 19.

If the plate not is flat, it is an advantage to have a large coppercontent in the plate. since copper is easier to shape with formingmethods than the high temperature steels commonly used. Shaping ispossibly needed to make the plate follow a not plane load carryingstructure.

The cooling channels 20 may be provided by wire-electro dischargemachining the channels out of a solid sheet forming the second wall 18,thereby also resulting in the provision of the webs 20. In case a partof or the whole first wall 17, 117 is made of the same material as thesecond wall 18 and the webs 19, also the first wall 17, 117 or part ofit could be part of that one and the same sheet in which the channels 20are formed by means of wire-electro discharge machining. Wire-electrodischarge machining is a preferred solution compared to pin milling ordisc milling for very narrow slots.

FIG. 7 shows a liner 216 according to prior art, in which thewidth/height ratio of the channels 220, as seen in a cross section ofthe liner, is 8.3 or more. The liner 216 is provided close to aload-carrying frame 212, and comprises a first wall 217, a second wall218 and webs 219 that interconnect aid first and second walls 217, 218,thereby defining said channels 220.

It should be understood that the above description of preferredembodiments has been made in order exemplify the invention, and thatalternative solutions will be obvious for a person skilled in the art,however without departing from the scope of the invention as defined inthe appended claims supported by the description and the drawings.

For example, the liner 16, 116 according to the invention may becovering only parts of the load-carrying frame 12, while other parts arecovered by a conventional liner, for example like the one shown in FIG.7. Moreover, the materials of the parts of the load-carrying frame 12 aswell as the liner 16, 116 may be other than those suggested herein.Likewise, the arrangement of the liner 16, including its fixing and thedistance thereof to the adjacent load-carrying frame, will be a designissue for every individual application and may, therefore, differ fromconstruction to construction.

1. A liner for a turbine section, the liner comprising a first wall, aplurality of webs interconnected with and projecting from the firstwall, and a plurality of cooling channels, each of the cooling channelsbeing delimited by two adjacent webs and the first wan, wherein eachcooling channel presents a height corresponding to the height of itsdelimiting webs, and a width corresponding to the distance between itsdelimiting webs, wherein at least one of the cooling channels has awidth/height ratio of below 5, wherein the material of the webs has ahigher thermal conductivity than the material of the first wall.
 2. Aliner according to claim 1, wherein the width/height ratio is below 3.3. A liner according to claim 1, wherein the width/height ratio isbelow
 1. 4. A liner according to claim 1, wherein the width/height ratiois below 0.5.
 5. A liner according to claim 1, wherein the width/heightratio is above 0.1.
 6. A liner according to claim 1, wherein, for the atleast one channel, the ratio between the width of the at least onechannel and the width of at least one of its delimiting webs is <2.
 7. Aliner according to claim 1, wherein the width of each of the webs thatdelimit the at least one channel is below 2 mm.
 8. A liner according toclaim 1, wherein the height of the at least one channel is above 2 mm.9. A liner according to claim 1, wherein the height of the at least onechannel is below 15 mm.
 10. A liner according to claim 1, wherein itcomprises a second wall interconnected with the first wall through atleast some of the webs and located opposite to the first wall.
 11. Aliner according to claim 1, wherein the material of the first wall has ahigher temperature resistance than the material of the webs.
 12. A lineraccording to claim 1, wherein the material of the first wall comprisessteel.
 13. A liner according to claim 1, wherein the material of thewebs comprises copper as a main constituent.
 14. A liner for a turbinesection, the liner comprising a first wall, a plurality of websinterconnected with and projecting from the first wall, and a pluralityof cooling channels, each of the cooling channels being delimited by twoadjacent webs and the first wall, wherein the material of the webs has ahigher thermal conductivity than the material of the first wall.
 15. Aliner according to claim 14, wherein the material of the first wall hasa higher temperature resistance than the material of the webs.
 16. Aliner according to claim 14, wherein the material of the first wallcomprises steel.
 17. A liner according to claim 14, wherein the materialof the webs comprises copper as a main constituent.
 18. A lineraccording to claim 14, wherein it comprises a second wall interconnectedwith the first wall through at least some of the webs and locatedopposite to the first wall.
 19. A turbine section, comprising a lineraccording to claim
 14. 20. A turbine section according to claim 19,wherein the first wall of the liner is directed such that it will bedirectly subjected to hot gases flowing through the turbine sectionduring turbine operation.
 21. A turbine section according to claim 19,wherein the liner is attached to a load-carrying part of the turbinesection.
 22. A turbine section according to claim 21, wherein theload-carrying part of the turbine section comprises a radial strutconnecting an inner wall and an outer wall of the turbine section.
 23. Aturbine section according to claim 21, wherein the load-carrying part ofthe turbine section comprises an inner wall of the turbine section. 24.A turbine section according to claim 21, wherein the load-carrying partof the turbine section comprises an outer wall of the turbine section.25. A turbine section according to claim 19, wherein the turbine sectioncomprises a load-carrying frame arranged adjacent to at least one gasturbine.
 26. A turbine section according to claim 19, wherein itcomprises means for introducing a flow of a cooling medium into thechannels, and means for letting the cooling medium out of the channels.27. A gas turbine engine, comprising a turbine section according toclaim
 19. 28. An aeroplane, comprising a turbine engine according toclaim 27.